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lib/pkp/classes/core/Registry.php

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+<?php
+
+/**
+ * @file classes/core/Registry.php
+ *
+ * Copyright (c) 2014-2021 Simon Fraser University
+ * Copyright (c) 2000-2021 John Willinsky
+ * Distributed under the GNU GPL v3. For full terms see the file docs/COPYING.
+ *
+ * @class Registry
+ *
+ * @ingroup core
+ *
+ * @brief Maintains a static table of keyed references.
+ * Used for storing/accessing single instance objects and values.
+ */
+
+namespace PKP\core;
+
+class Registry
+{
+    /**
+     * Get a static reference to the registry data structure.
+     *
+     */
+    public static function &_getRegistry(): array
+    {
+        static $registry = [];
+        return $registry;
+    }
+
+    /**
+     * Get the value of an item in the registry (optionally setting a default).
+     *
+     * @param bool $createIfEmpty Whether or not to create an entry if none exists
+     * @param mixed $default If $createIfEmpty, this value will be used as a default
+     */
+    public static function &get(string $key, bool $createIfEmpty = false, mixed $default = null): mixed
+    {
+        $registry = & self::_getRegistry();
+
+        if (isset($registry[$key])) {
+            return $registry[$key];
+        }
+        if ($createIfEmpty) {
+            self::set($key, $default);
+        }
+        return $default;
+    }
+
+    /**
+     * Set the value of an item in the registry.
+     */
+    public static function set(string $key, mixed &$value): void
+    {
+        $registry = & self::_getRegistry();
+        $registry[$key] = & $value;
+    }
+
+    /**
+     * Remove an item from the registry.
+     */
+    public static function delete(string $key): void
+    {
+        $registry = & self::_getRegistry();
+        if (isset($registry[$key])) {
+            unset($registry[$key]);
+        }
+    }
+
+    /**
+     * Clear the registry of all contents.
+     */
+    public static function clear(): void
+    {
+        $registry = & self::_getRegistry();
+        foreach (array_keys($registry) as $key) {
+            unset($registry[$key]);
+        }
+    }
+}